Studies on the phytoplankton of inshore and offshore waters off Colombo and some data on the hydrological conditions of these waters

The present paper gives a comparative account of the hydrological conditions and phytoplankton within the Continental Shelf and beyond the Continental Shelf. 54 water samples were taken for hydrological analysis and 18 surface tows for plankton.

Studies on the seasonal cycle of sea surface temperatures, salinities, oxygen and phytoplankton in Koddiyar Bay, Trincomalee in relation to the shore seine fishery

In Sri Lanka waters, Durairatnam (1963, 1969) had reported on the seasonal variation of plankton at Puttalam lagoon, Dutch Bay, Portugal Bay and in the inshore and off shore waters off Colombo. Similar investigations were carried out at Koddiyar Bay especially in the estuarine waters where the three tributaries of the river Mahaveli empty their waters into the bay. The estuary is perennial. The fishes constituting the estuarine fisheries are mostly shallow water marine species which can tolerate considerable variations of salinities. Prawns and crabs also constitute a very valuable fishery in estuarine waters.

Results of the Austrian-Ceylonese hydrobiological mission 1970 of the 1st Zoological Institute of the University of Vienna (Austria) and the Department of Zoology of the Vidyalankara University of Ceylon, Kelaniya. Pt. 2. Hydrochemical studies on mountain rivers in Ceylon

The morphology, climate, geology and geochemistry of Sri Lanka is briefly described. The separation into a wet zone (the south-west and greater part of the central highland) and a dry zone with two very dry parts in the south-east and in the north-west, is obvious and has great influence on the hydrochemistry of the island. Geology is very homogenous (Precambrian crystalline series) and some Jurassic and Miocene limestones (only in the north).

Studies on the fish ponds at Pitipana, Negombo 1: seasonal and diurnal variation of some hydrobiological factors

The present paper is a part of a detailed investigation on the biology of grey mullet, Mugli cephalus L., and the feasibility of its culture in the brackish waters of Sri Lanka. The authors present the results of investigation on the water quality of five experimental ponds at the Pitipana Brackishwater Fisheries Station, Negombo, carried out over a period of one year, December 1976 to November 1977, together with studies on the primary productivity are presented.

Studies on the preparation of fish silage. 1. Effect of quality of raw material and type of acid

An experiment was undertaken in which silver bellies (Leiognathus splendens) of different quality were used to produce silages using different concentrations of hydrochloric acid and formic acid. The quality and storage life of the various preparations are reported. Silages which keep for at least 30 days can be produced from silver belly held for 3 or 12 hours at 28°C by: 1) reducing the pH by addition of hydrochloric acid; 2) adding 0.5% formic acid and reducing the pH to 3.5 with hydrochloric acid; or 3) adding 2.5% formic acid.

Studies on fecundity of Puntius sarana (Ham.) in relation to total length, total weight and ovary weight

A total of 43 mature female of Puntius sarana (Ham.) ranging from 204 mm to 320 mm in length and 102 to 482 g in weight were used for present studies. The relationship between fecundity with respect to total length (TL), total weight (TW) and ovary weight (OW) was found to be linear. The coefficient of co-relation 'r' of the above relationships was found to be 0.5947, 0.5761 and 0.9837 respectively. All these values are highly significant (P=0.01) indicating a close relationship between these parameters. However, as indicated by value of 'r' (0.9837), the fecundity is more closely related to ovary weight and hence the ovary weight may be a better index of fecundity than the total length or weight.

Effect of lykamin on growth and biochemical composition of long whiskered catfish, Mystus gulio (Hamilton) fingerlings under laboratory conditions

A growth trial was conducted to test the effect of Lykamin (dietary supplement) on growth, survival and feed conversion in Mystus gulio. Four isoproteic diets were formulated by incorporating the growth promoter, Lykamin at the levels of 0, 0.25, 0.50 and 0.75% diet. The crude protein content was 30% in each diet. The diets were fed to triplicate groups of catfish fingerlings twice daily at a level of 5% of the total body weight for 120 days. Regular fortnightly sampling was done to evaluate the growth performance of the experimental animals. Water quality parameters during the experimental period were maintained within the range suitable for catfish. The results showed better specific growth rate, weight gain, protein efficiency ratio and feed conversion ratio in the group which was given 0.75% Lykamin diet.

Studies on fecundity of Rita pavimentata (Gunther) in relation to total length, total weight and ovary weight

A total of thirty eight ripe ovaries from the specimens of Rita pavimentata, measuring 230 to 355 mm in total length (TL) and 250 to 750 g in total weight (TW), were selected to study the fecundity. The relationship between fecundity 'and total length (TL), total weight (TW) and ovary weight (OW) was found to be linear. The coefficient of co-relation 'r' of the above relationship was found to be 0.92, 0.94 and 0.96 respectively. All these values are highly significant (P=0.01) indicating a close relationship between compared parameters. However, as indicated by value of 'r' (0.96), the fecundity is more closely related to ovary weight and hence the ovary weight may be a better index of fecundity than the total body length or weight.

Studies on geo-morphology, ecology and fish production of the 92 rivers of Rajshahi Division, Bangladesh

Geo-morphology, ecology and fish production of the 92 rivers of Rajshahi division have been presented in this paper. Fifteen rivers are dead and 11 rivers have severe erosion problem. Siltation has increased in 66 rivers and depth has decreased in 11 rivers. Sixty nine rivers are suffering from low flow conditions. Fish diversity has decreased in 20 rivers while fish production has declined in 75 rivers. A total of 31 fish species have extinct, 25 species are under threat of extinction and 43 species have low production. Siltation and pollution are the major causes of fish habitat loss. Recommendations are made to protect and conserve fish habitat and riverine fisheries of Rajshahi division.

Studies on the age and growth of Labeo calbasu (Hamilton) with an exploitation pattern from the Ganga River system, Uttar Pradesh (India)

Samples were collected to study the age and growth of Labeo calbasu (Hamilton) from the river Ghaghra (Guptarghat centre, Faizabad). The scales of L. calbasu have been used for age and growth studies in present paper. Study of the marginal rings on the scales of L. calbasu indicates their annual nature. The fish attained growth in 1st 18.7 cm, 2nd 27.8 cm, 3rd 35.7 cm, 4th 41.8 cm, 5th 46.9 cm, 6th 54.9 cm and 7th 57.4 cm years of the life. The growth rate was observed 18.7, 9.1, 7.9, 6.7, 5.1, 8.0 and 2.5 cm for 1st to 7th age classes respectively. The age groups 1+ to 4+ constituted 91.17% of the total exploited population and 8.83% of remaining age groups (5+ to 7+). The maximum exploited population was observed in 2+ age group with 33.68%. Overall exploitation pattern was systematic and a good indicator for heavy recruitment.

Studies on water quality and fish diversity of Sadatpur lake in Ahmednagar district Maharashtra

The present study deals with the water quality and ichthyofauna of Sadatpur lake. Monthly changes in water quality parameters such as temperature, pH, dissolved oxygen (DO), total alkalinity, chlorides, sulphates, phosphates and nitrites have been studied for a period of one year beginning from January 2005 and were investigated to assess the suitability of this lake for fish and fisheries practices. All the physico-chemical parameters determined, revealed that the fluctuations in water temperature, pH, dissolved oxygen, alkalinity and nitrites, were within the desirable limits. On the other hand, chloride and sulphate were lower whereas phosphate was higher than the desirable limits. Altogether 24 fish species belonging to 17 genera and 2 orders were found to be present in the lake. Among fish species family Cyprinidae dominated the lake. The lake subsistence fishery served the need of local fishermen community.

Studies on frozen storage characteristics of fillets from six species of fresh water fishes

Frozen storage characteristics of fillets from six major species of fresh water fishes namely, Labeo rohita, Catla catla, Cirrhina mrigala, Labeo calbasu, Mystus seenghala, and Wallago attu are reported. The biochemical, bacteriological and organoleptic changes in the frozen fillets during storage at -18°C have been followed systematically. Compared to the two species of fresh water cat fishes, the four species of carps studied, had a slightly better storage life. From the organoleptic point of view, fillets of Cirrhina mrigala had the best shelf life.

Studies on the influence of moisture and specific gravity on the strength properties of mango wood (Mangifera indica)

Influence of moisture and specific gravity on the strength of mango wood is discussed. The co-efficient of correlation between specific gravity and breaking strength was found to be non-significant. The relation of strength and moisture was found to be highly significant. The mean strength values indicated a reduction in strength when the moisture increased from 8.5 to 18.8%. However no appreciable difference in strength values could be observed when moisture increased above 37%. The strength-moisture relationship is a straight line, passing approximately through the fibre saturation point. By using the exponential formula, the breaking strength corresponding to any moisture level between zero and fibre saturation can be determined.

Studies on smoke curing and preservation of oil sardine (Sardinella longiceps)

A method is reported for smoke curing of oil sardine (Sardinella longiceps) by dry salting in the ratio of 1:6 (salt to fish), followed by smoking in the traditional smoke chamber in two stages, (1) at 45°C for 3h hand (2) at 75°C for 2h with smoke generated from coconut husk, wood shavings and saw dust in 2:2:1 proportion. The product obtained had good odour, flavour, golden yellow colour and a shelf-life of 8 weeks at room temperature (26 to 28°C)

Studies on aminotransferase enzymes in fish and shellfish

The distribution of aspartate aminotransferase (AAT) and alanine aminotransferase (ALAT) activities in the skeletal muscle of several fish species is reported. AAT activity is found higher than ALAT activity and that the red muscle has higher aminotransferase activity than the white muscle. It is observed that 2-oxoglutaric acid has a wider scope as an amino group acceptor than pyruvic acid in the skeletal muscle of fish. The significance of transamination& in fish is discussed.